638615735440 has 40 divisors (see below), whose sum is σ = 1493672523840. Its totient is φ = 253916670336.

The previous prime is 638615735423. The next prime is 638615735497. The reversal of 638615735440 is 44537516836.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23886930 + ... + 23913649.

It is an arithmetic number, because the mean of its divisors is an integer number (37341813096).

Almost surely, 2^638615735440 is an apocalyptic number.

It is an amenable number.

638615735440 is an abundant number, since it is smaller than the sum of its proper divisors (855056788400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638615735440 is a wasteful number, since it uses less digits than its factorization.

638615735440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47800759 (or 47800753 counting only the distinct ones).

The product of its (nonzero) digits is 7257600, while the sum is 52.

The spelling of 638615735440 in words is "six hundred thirty-eight billion, six hundred fifteen million, seven hundred thirty-five thousand, four hundred forty".